ProjectSummary Emotionaldysfunctionisatthecoreofmanypsychiatricdisorders,inparticularfear,anxiety,post-traumatic, andmooddisorders.Describingtheneuralmechanismsassociatedwithemotionalprocessingisthereforea criticalissueinmentalhealthcare.Previousattemptstodefinetheneurophysiologyofhumanemotionsinthe cognitive neuroscience laboratory have been hampered by the unavailability of conceptual and methodological frameworks for studying complex emotional responses in context and with conflicting informationpresent.Theproposedresearchestablishesanoveltechniqueforcombiningelectrophysiological recordings, high in temporal precision, with functional brain imaging, which is high in spatial precision. This approach,calledsteady-statepotentialfrequency-tagging,achievesstimulusspecificity,temporal,andspatial resolutionacrossthewholebrain.Itisuniqueinthatitallowsresearcherstoidentifydistinctbrainnetworks selectivelyactivatedbydifferentelementsofacomplexvisualscene?evenwhentheelementsarespatially overlapping and accompanied by stimulation in other sensory modalities. We combine this innovative approachwithanovelconceptualframeworkthatconsiderschangesinvisualperceptionanactivepartofan observer?s emotional response, to address the following Aims: (1) We characterize the large-scale brain dynamics mediating the emotional response to an element that is embedded in a complex visual array. (2) We determine how conflicting appetitive and aversive information, visual and auditory, affects these brain dynamics. (3) Finally, we translate this novel method to socially anxious observers, testing mechanistic hypotheses regarding the interactive effects of trait anxiety and chronic stress on short-term reactivity to emotional challenge. The long-term clinical implications of the proposed research are manifold: For diagnosticassessmentandformonitoringtreatmentefficacy,aquantitativebrain-basedmarkerofemotional engagement opens avenues for objectively evaluating pre- to post-treatment changes in appetitive/aversive neural reactivity. It also enables measuring neural circuit function to enable quantitative measurements of specificpsychopathologyandforidentifyingtreatmenttargetsinapersonalizedmedicineframework.